Screen time in teenagers: how can we manage it?

• Screen time can impact on myopia development and progression, and is also linked to dry eye syndrome, digital eyestrain, and poor head and neck postures which can cause pain.
• Teenagers are recommended to have no more than 2 hours of sedentary, recreational screen time per day. This means leisure screen time, outside of school work.
• Discussing 'the elbow rule' and 'the 20/20 rule' with your teenager can help them to set up healthy habits for screen time supporting good vision, eye health and musculoskeletal comfort.

Screen time is a necessary part of teenagers' schooling and learning, and an ever-present part of their social lives, too. A recent report found that teenagers spend an average of 8 hours 39 minutes per day on screens, compared to 5-and-a-half hours for pre-teen children. This time had increased more in the two years of the pandemic compared to the four years prior.

Lots of time spent on screens can be linked to development of vision problems, myopia, dry eyes and digital eyestrain in teenagers.

There are strong links between spending a lot of time looking up close - whether books or screens - and myopia. Myopia is an eye condition which causes blurred far vision, and is also known as short-sightedness or near-sightedness. Once myopia develops in children, it typically deteriorates every few to several months until the late teenage years and even into the early 20s.¹ Myopia is a significant concern to quality of life in teenagers, and poses a risk to long-term eye health.²

Screen time tends to encourage long durations of use and closer viewing distances than books.³ Research has shown than increased digital device time does lead to more myopia in children and teens, and even more when combined with computer use.⁴

Myopia is not the only concern when it comes to screen time. There are other effects that screen usage can have on vision and eye health. These can affect children, teenagers and adults with heavy screen usage.

1. Dry eyes: dry eye symptoms are associated with high amounts of myopia in teenagers,⁵ and teens with myopia have been shown to have higher digital device use than teens with normal vision.⁶ When using a screen, viewing at closer distances and when concentrating, we tend to blink less. This causes the front part of the eye that normally keeps the eye wet, healthy and comfortable (the tear film) to dry out. Dry eye can cause blurry vision, sore and red eyes, and interfere with comfortable contact lens wear. It is important this is managed well with your optometrist or eye doctor, as ‘dry eye’ sounds simple to fix, but can often be a complex and long-term condition.
2. Digital eyestrain: Headaches, blurry vision, sore or itchy eyes are symptoms of digital eyestrain. which has become more common in kids and teenagers, especially due to screen-based remote learning during the COVID pandemic.⁷ This can be due to a combination of dry eye symptoms, undiagnosed vision problems or other issues like glare sensitivity. Digital eyestrain is more likely to occur in teenagers over 14 years of age, if smartphones are used for games, used at closer viewing distances (less than 18 inches or 45cm) and for longer duration of device use (more than five hours per day).⁷
3. Eye muscle problems: Esotropia is an eye muscle condition whereby the eyes turn inwards and appear cross-eyed. One study reported on a case series of teenagers with previously normal eye muscle alignment who developed esotropia with smartphone use of more than 6 hours per day, at a viewing distance of less than 30 cm, for several months. Despite all having clear vision without or with glasses (if needed), most were noticing double vision symptoms. All showed some improvement after reducing their smartphone use, but some required eye muscle surgery to fix the esotropia.⁸

Reducing screen time is important not only for vision and eye health, as higher levels of screen time are also associated with mental and physical health issues in teenagers.⁹

Open family discussion about screen time is an important starting point, with researching showing that setting time- and activity-related goals leads to positive outcomes.⁸

The World Health Organization has made specific recommendations on screen time for children aged 4 and under, in relation to physical activity and sleep guidelines. It has produced guidelines on physical activity for children aged 5 and older and adults, but not on screen time. This recommendation becomes more complex in school-aged children, where screens are increasingly used in formal education settings. This means that limiting screen time which is purely for entertainment is important.

Screen time can encourage sedentary (immobile) behavior, which can have numerous impacts on physical and mental health in children. The World Health Organization recommends the following physical activity guidelines for children aged 5 to 17 years.

• At least an average of 60 minutes per day of moderate-to-vigorous intensity, mostly aerobic, physical activity, across the week.
• Incorporate vigorous-intensity aerobic activities, as well as those that strengthen muscle and bone, at least 3 days a week.
• Limit the amount of time spent being sedentary, particularly the amount of recreational screen time.

Blue-light blocking coatings on spectacle lenses (glasses) can reduce eye strain for some people, when spending a lot of time looking at back-lit screens. There is a small amount of evidence that they can improve sleep quality in people with self-reported insomnia, but may not have an effect in those with normal sleep patterns. Claims about these coatings protecting the health of the retina have not been supported by evidence.^11,12 The best advice is to pick this type of coating if your teenager feels more comfortable looking through it at a screen.

When it comes to eye health and reducing the risks of myopia, there are three simple rules to talk about with your teenager.

1. The elbow rule. This is where your teenager should try to keep an elbow-to-wrist distance between anything they are viewing up close, and their eyes. Try it yourself, and show them at home – make a fist, put it next to your eyes, and where your elbow sits is the closest any screen or book should get to your eyes when reading. This helps to avoid very close viewing distances (less than 20-30cm) which are associated with increased visual effort, development of myopia,¹³ and eye muscle coordination problems.⁸
2. The 20/20 rule. This is where your teenager aims to take a break from reading or screen work every 20 minutes, for 20 seconds. He or she should look across the room for those 20 seconds, to relax the focussing muscles in the eyes before recommencing reading or screen time. This is to avoid prolonged time spent in close-up vision, as more than 45 minutes without a break has been linked to myopia.¹³
3. The two-hour rule. This is limiting leisure or recreational screen time, outside of school work, to less than 2 hours per day.

• Talk to your teen about setting screen timers. This is easy to do in digital device settings, and can be customized to lock out of certain apps after certain duration or times of day, to help your teen set their own boundaries.
• Be a good screen time role model yourself. Set your own timers and check in on your own habits. There is a strong link between parental screen time and that of their kids.¹⁴ Aim to set up screen-free times in the family day (eg. meal times) and screen-free places in the family home (eg. the dinner table and teenagers’ bedrooms, where possible).

1. Hou W, Norton TT, Hyman L, Gwiazda J; COMET Group. Axial Elongation in Myopic Children and its Association With Myopia Progression in the Correction of Myopia Evaluation Trial. Eye Contact Lens. 2018 Jul;44(4):248-259.
2. Tideman JW, Snabel MC, Tedja MS, van Rijn GA, Wong KT, Kuijpers RW, Vingerling JR, Hofman A, Buitendijk GH, Keunen JE, Boon CJ, Geerards AJ, Luyten GP, Verhoeven VJ, Klaver CC. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016 Dec 1;134(12):1355-1363.
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8. Lee HS, Park SW, Heo H. Acute acquired comitant esotropia related to excessive Smartphone use. BMC Ophthalmol. 2016 Apr 9;16:37.
9. Zhang Y, Tian S, Zou D, Zhang H, Pan CW. Screen time and health issues in Chinese school-aged children and adolescents: a systematic review and meta-analysis. BMC Public Health. 2022 Apr 22;22(1):810.
10. Gentile DA, Reimer RA, Nathanson AI, Walsh DA & Eisenmann JC. Protective effects of parental monitoring of children's media use: a prospective study. JAMA Pediatr (2014).
11. Downie LE. Blue-light filtering ophthalmic lenses: to prescribe, or not to prescribe? Ophthalmic Physiol Opt. 2017 Nov;37(6):640-643.
12. Lawrenson JG, Hull CC, Downie LE. The effect of blue-light blocking spectacle lenses on visual performance, macular health and the sleep-wake cycle: a systematic review of the literature. Ophthalmic Physiol Opt. 2017 Nov;37(6):644-654.
13. Li SM, Li SY, Kang MT, Zhou Y, Liu LR, Li H, Wang YP, Zhan SY, Gopinath B, Mitchell P, Wang N; Anyang Childhood Eye Study Group. Near Work Related Parameters and Myopia in Chinese Children: the Anyang Childhood Eye Study. PLoS One. 2015 Aug 5;10(8):e0134514.
14. Joshi A, Hinkley T. Too much time on screens? Screen time effects and guidelines for children and young people. Australian Institute of Family Studies, August 2021.